“Donald J. Trump has shaken up his presidential campaign for the second time in two months, hiring a top executive from the conservative website Breitbart News…

Stephen Bannon, the executive chairman of Breitbart News LLC, will become the Republican campaign’s chief executive, and Kellyanne Conway, a senior adviser and pollster for Mr. Trump and his running mate, Gov. Mike Pence of Indiana, will become the campaign manager.

Mr. Bannon has no experience with political campaigns, but he represents the type of bare-knuckled fighter that the candidate had in Corey Lewandowski, his combative former campaign manager, who was fired on June 20.

Mr. Bannon has been a supporter of Mr. Trump’s pugilistic instincts, which the candidate has made clear in interviews he is uncertain about suppressing. He is also deeply mistrustful of the political establishment, and his website has often been critical of Speaker Paul D. Ryan and Senator Mitch McConnell, the majority leader.”